Class UML 2.3::Extend

Description:

A relationship from an extending use case to an extended use case that
specifies how and when the behavior defined in the extending use case can
be inserted into the behavior defined in the extended use case.

Constraints:

Signature: extension_points() : Boolean;Description: The extension points referenced by the extend relationship must belong
to the use case that is being extended.Expression: extensionLocation->forAll (xp | extendedCase.extensionPoint->includes(xp))